Corrosion inhibition of polymethylpentene

ABSTRACT

The corrosion tendencies of polymers of 4-methyl-1-pentene, when combined with tris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate and bis(2,4-ditert-butyl)pentaerythritol diphosphite are reduced. Optionally, metal stearates and/or poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-5-triazine-2,4-diyl][2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[2,2,6,6-tetramethyl-4-piperidyl)imino]] can be added to further reduce the polymer corrosion tendencies.

This invention relates to homopolymers and copolymers of4-methyl-1-pentene.

It is known in the art that hindered phenols, organic diphosphites,and/or hindered amine light stabilizers, as antioxidants, can be addedto polyolefins to improve the polymer light, heat, and oxidationstability properties. Prior art also teaches that the addition of higherfatty acids and the corresponding metal salts of higher fatty acids canbe added to polyolefins, either alone or in combination with otheradditives, as lubricants. Other additives, such as corrosion inhibitors,can be added to polyolefins to improve a property of the polyolefin.Although the art uses the phrases "polyolefins" and "syntheticpolymers," the types of polymers referenced are usually those formedfrom linear alpha-olefins. Homopolymers and copolymers of branched,higher, alpha-olefins, such as 4-methyl-1-pentene, usually are notspecifically disclosed.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a composition comprisinghomopolymers and copolymers of 4-methyl-1-pentene,tris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate, andbis(2,4-ditert-butyl)pentaerythritol diphosphite that inhibits thecorrosive effects of the polymer.

It is another object of this invention to provide a compositioncomprising homopolymers and copolymers of 4-methyl-1-pentene,tris(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate, andbis-(2,4-ditert-butyl)pentaerythritol diphosphite, andpoly[[6-[(1,1,3,3-tetramethylbutyl)amino]-5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene-[2,2,6,6-tetramethyl-4-piperidyl)imino]]that inhibits the corrosive effects of the polymer.

It is yet a further object of this invention to provide a compositioncomprising stereoregular homopolymers and copolymers of4-methyl-1-pentene, tris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate,bis-(2,4-ditert-butyl) pentaerythritol diphosphite, and zinc stearate orcalcium stearate that inhibits the corrosive effects of the polymer.

It is yet another object of this invention to provide a method forprocessing homopolymers and copolymers of 4-methyl-1-pentene withreduced corrosion imparted to the processing apparatus.

It is yet another object of this invention to provide a method to coat ametal object with homopolymers and copolymers of 4-methyl-1-pentenewhereby corrosion of the metal object is reduced.

In accordance with the present invention,tris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate andbis-(2,4-ditert-butyl)pentaerythritol diphosphite are added tohomopolymers and copolymers of 4-methyl-1-pentene in amounts sufficientto reduce the corrosion tendencies of the homopolymer and copolymer. Inanother embodiment of the invention, zinc stearate, calcium stearate,and/orpoly[[6-[(1,1,3,3-tetramethylbutyl)amino]-5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene-[2,2,6,6-tetramethyl-4-piperidyl)imino]]are also added to the homopolymers and copolymers of 4-methyl-1-penteneto further reduce the polymer corrosion tendencies. In anotherembodiment of the invention, homopolymers and copolymers of4-methyl-1-pentene having reduced corrosion tendencies are used toencapsulate or coat a metal object or a metal-containing substrate.

DESCRIPTION OF PREFERRED EMBODIMENTS Polymers

This invention is particularly applicable to polymers which have amelting point higher than about 180° C., more preferably, a meltingpoint of greater than about 190° C. Polymers produced from linearmonomers, such as ethylene, propylene, butene, and hexene, usually havea lower melting point than polymers of branched, higher, stereoregularalpha-olefins. Thus, the polymers useful in this invention arehomopolymers and copolymers of 4-methyl-1-pentene, also calledpolymethylpentene (PMP). PMP has a melting point of about 240° C.

The term "polymer", as used in this invention, includes homopolymers, aswell as copolymers. Copolymers of PMP comprise the product resultingfrom polymerizing PMP in the presence of any other olefin monomer ormonomers. Generally, applicable comonomers have from about 2 to about 18carbon atoms preferably, have from about 8 to about 16 carbon atoms.Most preferably, the comonomer or comonomers are alpha-olefins. Longerchain olefins are preferred in that they are easier to copolymerize with4-methyl-1-pentene and can impart increased stability and strength tothe resultant polymer. Exemplary comonomers include, but are not limitedto, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, andother higher olefins.

In general, it is preferred for the polymer to comprise at least about85 mole percent moieties derived from 4-methyl-1-pentene, and morepreferably, at least about 90 mole percent. Most preferably, the polymercomprises at least about 95 mole percent moities derived from4-methyl-1-pentene, which results in a polymer of superior strength anda high melting point.

Additives

Chemical additives are frequently combined with olefin polymers toimprove selected desired physical properties of the polymer. Forexample, antioxidants can be added to improve heat, light, and oxidationstability. Numerous polymer antioxidant additives are commerciallyavailable and are usually selected from the group consisting of hinderedphenols, organic phosphites, hindered amine light stabilizers, andmixtures thereof. Other compounds can be used as antioxidants.Processing lubricants can also be added to enhance polymer properties.Examples of processing lubricants include, but are not limited to, fattyacids containing about 10 to about 20 carbon atoms and the metal saltsthereof. Usually, metal stearates and/or metal laurates are used asprocessing lubricants for polyolefins. If corrosion is a potentialproblem, one or more corrosion inhibitors can be added.

As defined for this disclosure, the stability of a polymer is anindication or measure of how the polymer is affected by external forces,such as, for example, light, heat and oxygen, acting on or reacting withthe polymer. Stability, in other words, is a measure or indication ofchanges occurring in and/or to the polymer. Corrosion is defined as anindication or measure of how corrosive the polymer composition is on thesurface of an article or mold, i.e., the affect a polymer has on adifferent object. Corrosion, therefore, is a measure or indication ofchanges caused by residual catalyst and polymerization by-products inthe polymer.

Surprisingly, it has been discovered that the combination of twospecific antioxidants to polymethylpentene impart corrosion inhibitingeffects. A composition comprising polymers of 4-methyl-1-pentene,tris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate, andbis-(2,4-ditert-butyl)pentaerythritol diphosphite produces a polymerhaving reduced corrosion tendancies than polymers of 4-methyl-1-pentenewithout these two specific antioxidants.

The addition of sufficient amounts oftris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate andbis-(2,4-ditert-butyl)pentaerythritol diphosphite to polymers of4-methyl-1-pentene can inhibit the corrosive effects ofpolymethylpentene. Generally, tris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate is present in the corrosion inhibited polymer in the rangeof about 0.1 to about 1 parts by weight oftris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate per 100 parts byweight of polymer (php) and bis-(2,4-ditert-butyl)pentaerythritoldiphosphite is present in the corrosion inhibited polymer in the rangeof about 0.1 to about 1 parts by weight ofbis-(2,4-ditert-butyl)pentaerythritol diphosphite per 100 parts byweight of polymer (php). Preferably,tris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate is present in thepolymer in the range of about 0.1 to about 0.3 php andbis-(2,4-ditert-butyl)pentaerythritol diphosphite is present in thepolymer in the range of about 0.2 to about 0.4 php. Most preferably,tris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate is present in thecorrosion inhibited polymer in the range of about 0.15 to about 0.25 phpand bis-(2,4-ditert-butyl)pentaerythritol diphosphite is present in thecorrosion inhibited polymer in the range of about 0.25 to about 0.35php. Too much of either the hindered phenol or the organic diphosphitecan decrease the polymer stability; the additives can act as aprodegradant to the polymer. An insufficient amount of either additivecan impart no corrosion inhibition effect to the polymer.

In addition to the basic composition of polymethylpentene,tris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate, andbis-(2,4-ditert-butyl)pentaerythritol diphosphite, additional compounds,or additives, can be added to further decrease or, even, totallyeliminate the corrosive effects of the polymethylpentene. Metalstearates, such as, for example, zinc stearate, calcium stearate, andmixtures thereof can be added to the polymethylpentene composition tofurther enhance corrosion inhibition. Metal stearates also can have alubricating effect on the polymer. The amount of metal stearate that canbe added to the polymethylpentene composition is any amount necessary tofurther reduce the corrosive effects of the polymer or any amount tosufficiently improve lubrication of the polymer. Generally, metalstearates can be present in the polymethylpentene composition in therange of about 0.05 to about 1 php, preferably, in the range of about0.05 to about 0.15 php. Most preferably, metal stearates are present inthe polymethylpentene composition in the range of about 0.07 to about0.13 php. Addition of metal stearates within these ranges maintains apolymer with appropriate clarity. Too much metal stearate can cloud thepolymer and too little metal stearate can impart no beneficial affect tothe polymer.

Hindered amine light stabilizers, such as, for example, polymerichindered amines like piperidenyl triazine polymers and piperidenyltriazine derivative polymers, when added to the inventive corrosioninhibiting polymethylpentene composition, can further reduce thecorrosion caused by the polymethylpentene. It has been found that theaddition of an appropriate amount ofpoly[[6-[(1,1,3,3-tetramethylbutyl)amino]-5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene-[2,2,6,6-tetramethyl-4-piperidyl)imino]]can completely eliminate the corrosive effects of the inventive4-methyl-1-pentene polymer composition. These types of piperidenyltriazine polymers are disclosed in U.S. Pat. No. 4,086,204, hereinincorporated by reference. Too muchpoly[[6-[(1,1,3,3-tetramethylbutyl)amino]-5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene-[2,2,6,6tetramethyl-4-piperidyl)imino]]can act as a prodegradant to the polymer and an insufficient amount ofpoly[[6-[(1,1,3,3-tetramethylbutyl)amino]-5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene-[2,2,6,6-tetramethyl-4-piperidyl)imino]]can result in no additional corrosion inhibiting effects. Generally,poly[[6-[(1,1,3,3-tetramethylbutyl)amino]-5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene-[2,2,6,6tetramethyl-4piperidyl)imino]]is present in the polymethylpentene composition in the range of about0.1 to about 1 php, and preferably, in the range of about 0.1 to about0.3 php. For most effective use ofpoly[[6-[(1,1,3,3-tetramethylbutyl)amino]-5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]] it is preferably added to the polymethylpentenecomposition in the range of about 0.15 to about 0.25 php.

As stated earlier, other additives optionally can be incorporated intothe corrosion inhibiting polymethylpentene to achieve additionallydesired beneficial polymer properties. General exemplary additivesinclude, but are not limited to, antioxidants, UV absorbers, nickelstabilizers, pigments, charges, plastifying agents, antistatic agents,flame retardants, lubricating agents, more anticorrosive agents, metalinhibitors, and the like.

Any of the additives herein discussed can be combined with polymers of4-methyl-1-pentene according to any method known in the art. Examples ofincorporation methods include, but are not limited to, dry mixing in theform of a powder, and wet mixing in the form of a solution or slurry. Inthese types of methods, the polymethylpentene can be in any form, suchas, for example, fluff, powder, granulate, pellet, solution, slurry,and/or emulsion.

POLYMER APPLICATIONS

The polymethylpentene compositions of the invention are especiallyadvantageous for use in any type of polymer processing equipment. ThePMP polymer comprisingtris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate andbis-(2,4-ditert-butyl)pentaerythritol diphosphite and any other desiredadditive can have a less corrosive effect on the processing equipmentthan does a PMP polymer without tris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate and bis-(2,4-ditert-butyl)pentaerythritol diphosphite.Examples of such equipment and equipment components include, but are notlimited to, all types of mixing vessels; storage vessels; blenders;mixers; pelletizers; extruders; transfer tubes; screws; spinnarets;barrels; cutting blades; hoppers; dies; molds, for use in thermoforming,injection, molding, blow molding, and rotomolding; spinning; and otherequipment surfaces likely to contact the PMP.

The PMP compositions of the invention are also especially advantageousfor encapsulating or coating a metal-containing substrate, or a metalobject. A composition comprising polymethylpentene,tris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate, andbis-(2,4-ditert-butyl)pentaerythritol diphosphite can have a lesscorrosive effect on a metal portion of a metal containing substrate ormetal object, than does polymethylpentene withouttris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate andbis-(2,4-ditert-butyl)pentaerythritol diphosphite. Examples of metalsthat can be coated or encapsulated with compositions of this inventioninclude, but are not limited to, copper, gold, silver, aluminum,chromium, titanium, iron, and steels, such as chromium plated steels,carbon steels, and stainless steels, and the like, and alloys thereof.

EXAMPLES Example 1

Polymethylpentene prepared by conventional commercially availablecatalysts and given a prophylactic charge of a 0.05 weight percentcharge of octadecyl-3-(3,5-ditert-4-hydroxyphenyl)propionate (sold asIrganox 1076, available from Ciba-Geigy Corp.) in hexane solution wassubjected to an accelerated corrosion test described as follows:

The polymer to be tested for corrosion is compression molded against a1.25" diameter disk of mild carbon steel (SAE 1200) at 32,600 psi(40,000 lbs total force) for a 15 minute time period at an elevatedtemperature. The temperature of the compression molding step depends onthe polymeric material being evaluated. If the polymer to be tested ispolypropylene, the temperature used is 500° F. (260° C.) while if thepolymer to be tested is polymethylpentene, the temperature used for thetest is 550° F. (288° C.). The samples are allowed to cool to ambienttemperature before removing the polymer and steel disk from the samplepress. When cooled, the polymer is separated from the disk and the diskplaced in a desiccator at 100% relative humidity for 18±2 hours. At thecompletion of the test, the sample disk is removed from the dessicatorand visually compared for pitting corrosion to a uniquely developedseries of nine SAE 1200 mild carbon steel disks systematically varyingin the extent of pitting corrosion ranging in value from 0 to 4 by halfsteps with 0 showing no pitting corrosion and 4 showing the greatestpitting corrosion.

A corrosion number of 3.5 was obtained as a result and provides a basisfor comparison of polymethylpentene treated with various additivecompounds in Examples 2 through 8.

Example 2

Polymethylpentene, prepared and charged as in Example 1, was blendedwith 0.2 parts by weight oftris-(3,5-ditert-butyl-4-hydroxylbenzyl)isocyanurate (sold as Goodrite3114, available from Goodrich Chemical Co.; now sold as Irganox 3114,available from Ciba-Geigy Corp.) per 100 parts by weight of polymer(php) and subjected to the corrosion test described in Example 1; theresulting corrosion was found to be less than that observed in Example,1 being 3.0.

Example 3

Polymethylpentene, prepared and charged as in Example 1, was blendedwith 0.3 php bis-(2,4-ditert-butyl)pentaerythritol diphosphite (sold asUltranox 626, available from Borg-Warner Chemical Co.) and subjected tothe corrosion test described in Example 1; the resulting corrosion wasfound to be less than that observed in Example 1, being 2.5.

Example 4

Polymethylpentene, prepared and charged as in Example 1, was blendedwith 0.2 php tris-(3,5-ditert-butyl-4 hydroxybenzyl)isocyanurate and 0.3php bis-(2,4-ditert-butyl)pentaerythritol diphosphite and subjected tothe corrosion test described in Example 1; the resulting corrosion wasfound to be less than observed in Example 1, being 2.0.

Example 5

Polymethylpentene prepared and charged as in Example 1, was blended with0.3 php bis-(2,4-ditert-butyl)pentaerythritol diphosphite, 0.2 phptris-(3,5-ditert-butyl-4 hydroxybenzyl)isocyanurate, and 0.1 php zincstearate and subjected to the corrosion test described in Example 1; theresulting corrosion was found to be less than that observed in Example1, being 1.5.

Example 6

Polymethylpentene, prepared and charged as in Example 1, was blendedwith 0.3 php bis-(2,4-ditert-butyl)pentaerythritol diphosphite, 0.2 phptris-(3,5-ditert-butyl-4 hydroxybenzyl)isocyanurate, and 0.2 phppoly[[6-[(1,1,3,3-tetramethylbutyl)amino]-5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene-[2,2,6,6-tetramethyl-4-piperidyl)imino]](sold as Chimassorb 944, available from Ciba-Geigy Corp.) and subjectedto the corrosion test described in Example 1; the resulting corrosionwas found to be less than that observed in Example 1, being 0.0, that isno detectable corrosion was observed.

Example 7

Polymethylpentene, prepared and charged as in Example 1, was blendedwith 0.3 php bis-(2-4-ditert-butyl)pentaerythritol diphosphite, 0.2 phptris-(3,5-ditert-butyl-4hydroxybenzyl)isocyanurate, and 0.2 phpbis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate (sold as Tinuvin 770,available from and subjected to the corrosion test described in Example1; the resulting corrosion was found to increase by comparison Example4, being 3.0.

Example 8

Polymethylpentene, prepared and charged as in Example 1, was blendedwith 0.3 php bis-(2,4-ditert-butyl)pentaerythritol diphosphite, 0.2 phptris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate, and 0.2 phphexadecyl-3,5-di-tert-butyl-4-hydroxy benzoate (sold as UV 2908,available from American Cyanamid Co.) and subjected to the corrosiontest described in Example 1; the resulting corrosion was found toincrease by comparison to Example 4, being 2.5.

Example 9

Polypropylene, prepared by conventional commercially available catalystscontaining a prophylactic charge of 0.015 phpoctadecyl-3-(3,5-ditert-butyl-4-hydroxyphenyl)propionate in hexanesolution, was subjected the corrosion test of Example 1 with the resultthat a corrosion number of 2.0 was obtained as a result and provides abasis for comparison of polypropylene treated with various additivecompounds in Examples 10 through 13.

Example 10

The additive used in Example 2 was blended at the same php level withpolypropylene, which was prepared and charged as in Example 9, and wassubjected to the corrosion test of Example 1 with the result that noimprovement in corrosion resistance was obtained, the result being 2.0.

Example 11

The additive used in Example 3 was blended at the same php level withpolypropylene, which was prepared and charged as in Example 9, and wassubjected to the corrosion test of Example 1 with the result that noimprovement in corrosion resistance was obtained, the result being 2.0.

Example 12

The additives used in Example 4 were blended at the same php levels withpolypropylene, which was prepared and charged as in Example 9, and wassubjected to the corrosion test of Example 1 with the result that noimprovement in corrosion resistance was obtained, the result being 2.0.

Example 13

The additives used in Example 5 were blended at the same php levels withpolypropylene, which was prepared and charged as in Example 9, and wassubjected to the corrosion test of Example 1 with the result thatcorrosion was decreased slightly to a value of 1.5 from the referencevalue of 2.0 for polypropylene.

Example 14

Polypropylene, prepared by a commercially available catalyst similar tothat of Examples 9 through 13, containing a prophylactic charge of 0.015php octadecyl-3-(3,5-ditert-butyl-4-hydroxyphenyl)propionate in hexanesolution, was subjected to the corrosion test of Example 1 with theresult that a corrosion numbers of 0.5 was obtained.

Example 15

Polypropylene, prepared and charged as in Example 14, was blended with0.2 php tris- (3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate, 0.3 phpbis-(2,4-ditert-butyl)pentaerythritol diphosphite, and 0.2 phppoly[[6-[(1,1,3,3-teteramethylbutyl)amino]-5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene-[(2,2,6,6-tetramethyl-4-piperidyl)imino]]and subjected to the corrosion test of Example 1, with the result that acorrosion number of 1.0 was obtained.

Example 16

The composition of the polymethylpentene, as described in Example 4,improved the melt flow of the resulting treated polymer. Repelletizingpolymer from the first melt flow test and subjecting it to a second meltflow test increased the melt flow. Polymethylpentene treated with thestabilizers of Example 4 showed a reduced secondary melt flow relativeto unstabilized polymethylpentene. Polymethylpentene from the secondmelt flow test was repelletized and subjected to a third melt flow test.Again the tertiary melt flow values are lower for stabilizedcompositions relative to unstabilized compositions. The melt flow testis a variation of ASTM D 3835-79, run at 260° C. with a 5 kg weight.These values may be more easily understood by reference to the followingtable:

                  TABLE I                                                         ______________________________________                                        Initial and Sequential Melt Flows of Stabilized and                           Unstabilized Polymethylpentene Polymer                                                     Melt Flows                                                                                        Terti-                                                                              Corro-                                 Composition    Initial Secondary ary   sion                                   ______________________________________                                        Polymethylpentene (PMP)                                                                      28      36        58    3.0                                    PMP + 0.2 php A.sup.(1) +                                                                    10      14        18    1.5                                    0.3 php B.sup.(2)                                                             PMP + 0.2 php A +                                                                            8       12        16    1.5                                    0.3 php B + 0.05 php C.sup.(3)                                                PMP + 0.2 php A +                                                                            8       11        14    1.0                                    0.3 php B + 0.1 php C                                                         PMP + 0.2 php A +                                                                            7       11        14    1.5                                    0.3 php B + 0.1 php D.sup.(4)                                                 PMP + 0.2 php A +                                                                            7       11        13    2.5                                    0.3 php B + 0.1 php E.sup.(5)                                                 ______________________________________                                         Notes to Table 1                                                              .sup.(1) A is tris(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate              .sup.(2) B is bis(2,4ditert-butyl)pentaerythritol diphosphite                 .sup.(3) C is zinc stearate                                                   .sup.(4) D is calcium stearate                                                .sup.(5) E is 2,6ditert-butyl-paracresol (sold as BHT, available from         Uniroyal Chemical Co.) Melt flows were determined using ASTM procedure D      383579, at 260° C. with a 5 kg weight                             

Examples 2 and 3 show how an isocyanurate anti-oxidant for polymers or adiphosphite anti-oxidant for polymers act to impart corrosion stabilityto polymethylpentene by reference to Example 1. Examples 10 and 11demonstrate that these same polymer anti-oxidant compounds, used inExamples 2 and 3 to impart a corrosion resistance to polymethylpentene,do not impart a corrosion resistance to polypropylene by reference toExample 9. Example 4 shows that the combination of an isocyanurateanti-oxidant compound and a diphosphite anti-oxidant compound imparts inimproved corrosion resistance to polymethylpentene relative to their usesingly, as in Examples 2 and 3. Example 5 shows that adding metalstearate lubricant compounds to the combination of Example 4 furtherimproves the corrosion resistance of the polymethylpentene. Example 6shows that adding a hindered amine light stabilizer compound to thecombination of Example 4 improves the corrosion resistance ofpolymethylpentene to the point that no corrosion is observed in thecorrosion test used in Example 1. Examples 7 and 8 demonstrate thatvarious other anti-oxidant compounds do not necessarily impart corrosionresistance to polymethylpentene as shown in Examples 2 through 5.Example 12 shows that the combination of Example 4, effective forimparting corrosion resistance to polymethylpentene are ineffective inimparting corrosion resistance to polypropylene. Example 13 shows thatthe addition of a metal stearate lubricant compound to the combinationof Example 12 produces a slight improvement in the corrosion resistanceof polypropylene. Comparison of Examples 14 and 15 with Examples 1 and 6show that the additives used in Examples 6 and 15 are effective withpolymethylpentene and ineffective with polypropylene. Example 16 showsthat the combination of Example 4 produces additional benefits to thepolymethylpentene by reducing the initial and sequential melt flows ofthe polymer.

While this invention has been described in detail for the purpose ofillustration, it is not to be construed as limited thereby but isintended to cover all changes and modifications within the spirit andscope thereof.

That which is claimed is:
 1. A polymer composition having reducedcorrosion tendencies comprising:(a) a polymer selected from homopolymersand copolymers of 4-methyl-1-pentene; (b)tris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate; (c)bis-(2,4-ditert-butyl)pentaerythritol diphosphite and (d)poly[[6-[1,1,3,3-tetramethylbutyl)amino]-5-triazine-2,4-diyl][(2,2,6,6,-tetramethyl-4-piperidyl)imino]]hexamethylene[2,2,6,6,-tetramethyl-4-piperidyl)imino]].2. A polymer composition according to claim 1 wherein saidtris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate is present in therange of about 0.1 to about 1 parts by weight per 100 parts by weighthomopolymer or copolymer and said bis-(2,4-ditert-butyl)pentaerythritoldiphosphite is present in the range of about 0.1 to about 1 parts byweight per 100 parts by weight homopolymer or copolymer.
 3. A polymercomposition according to claim 1 wherein saidtris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate is present in therange of about 0.1 to about 0.3 parts by weight per 100 parts by weighthomopolymer or copolymer and said bis-(2,4-ditert-butyl)pentaerythritoldiphosphite is present in the range of about 0.2 to about 0.4 parts byweight per 100 parts by weight homopolymer or copolymer.
 4. A polymercomposition according to claim 1 wherein saidtris(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate is present in therange of about 0.15 to about 0.25 parts by weight per 100 parts byweight homopolymer or copolymer and saidbis-(2,4-ditert-butyl)pentaerythritol diphosphite is present in therange of about 0.25 to about 0.35 parts by weight per 100 parts byweight homopolymer or copolymer.
 5. A polymer composition according toclaim 1 further comprisingpoly[[6-[(1,1,3,3-tetramethylbutyl)amino]-5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene-[2,2,6,6-tetramethyl-4-piperidyl)imino]],metal stearates.
 6. A polymer composition according to claim 5 whereinsaidpoly[[6-[(1,1,3,3-tetramethylbutyl)amino]-5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene-[2,2,6,6-tetramethyl-4-piperidyl)imino]]are present in the range of about 0.1 to about 1 part by weight per 100parts by weight homopolymer or copolymer.
 7. A polymer compositionaccording to claim 5 wherein said metal stearates are present in therange of about 0.05 to about 1 part by weight per 100 parts by weighthomopolymer or copolymer.
 8. A polymer composition according to claim 5wherein said metal stearates are selected from the group consisting ofzinc stearate, calcium stearate, and mixtures thereof.
 9. A methodcomprising processing the polymer composition of claim 1 wherein saidcomposition impart reduced corrosion to the processing apparatus used insaid processing, compared to the corrosion imparted by said4-methyl-1-pentene without saidtris-(3,5-ditert-butyl-4-hydroxybenzyl)isocyanurate,bis-(2,4-ditert-butyl)pentaerythritol diphosphite and (d)poly[[6-[1,1,3,3,-tetramethylbutyl)amino]-5-triazine-2,4-diyl][2,2,6,6,-tetramethyl-4-piperidyl)imino]hexamethylene[2,2,6,6-tetramethyl-4-piperidyl)imino]].
 10. A method according toclaim 9 wherein said processing comprises extruding said composition.11. A method comprising encapsulating a metal object whereby corrosionis reduced by using the polymer composition of claim
 1. 12. A methodcomprising coating a metal object whereby corrosion is reduced by usingthe polymer composition of claim 1.